Variable crank-motion



(No Model.) 3 Sheets-Sheet 1.

A. KITSON. VARIABLE CRANK. MOTION.

No. 460,642. Patented Oct. 6, 1891.

t QWWK I m (No Model.) 3 Sheets-Sheet 2.

A. KITSON.

VARIABLE CRANK MOTION.

m: uomsmzrens 00,, ware-1mm, msmucwu, n. c.

(No Model.) 3 Sheets-Sheet 3. A. KITSON.

VARIABLE GRANK MOTION.

Patented Oct. 6, 1891.

My PM vzrsus cu. rncnvumo" WASHINGTON, o. c.

desired. In fact, it is deleterious.

UNITED STATES PATENT OFFICE.

ARTHUR KITSON, OF PHILADELPHIA, PENNSYLVANIA.

VARIABLE CRANK-MOTION.

SPECIFICATION forming part of Letters Patent No. 460,642, dated October 6, 1891. Application filed December 31, 1890- Serial No. 376,332. (No model.)

To all whom it may concern.-

. Be it known that I, ARTHUR KITSON, asubjectof the Queen of Great Britain, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Variable Crank-Motions; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to that class of mechanisms, of which gas-engines form an example, in which it is desired to give the piston a variable motion, sending it to the end of the cylinder on certain strokes and only 7 part way on other strokes.

In the drawings, Figure 1 is a side view and partial section of a portion of a gas-engine with my invention applied thereto. Fig. 2 is a detail section of the crank. Fig. 3 is a modification. Figs. 4. and 5 are details of the modification. Fig. 6 is another modification with connections for operating the exhaust-valve. Figs. 7, 8, 9, and 10 represent another modification at different points in its operation.

The particular application of my variable crank-motionthat is to say, in gas-engines which I shall hereinafter describe, is designed to obviate certain difficulties which arise when a poor quality of gas is used in the ordinary form of gas-engine having a regular and uniform piston motion. In the usual form of gas engine, in which a compression-space is left at the end of the cylinder, into which space the piston never enters, a certain portion of burned gases is left in the cylinder after each exhauststroke, which mixes with the incoming charge and helps to dilute it. When a gaseous mixture, having a small proportion of combustible gas in it, is used, further dilution is not It then becomes desirable to expel all the burned gases on the exhaust-stroke, so that a complete cylinder'full of fresh gas may be taken in. This is then compressed on the return stroke and exploded. To insure this complete emptying of the cylinder on one stroke, the piston must travel the entire length of the cylinder. On the next or compression stroke the charge of gas is trapped in the cylinder and the piston must stop before it reaches the end of the cylinder, leaving a space of one-third or The eccentric G is mounted on a sleeve S,

which turns upon the crank-pin p.

Rigidly connected to the sleeve S are the gear-wheels F and F. Meshing with these gear-wheels are stationary pinions E E. I

These pinions are mounted on spindles, such d d, which are prevented from turning by some attachment to some portion of the engine-bed--such, for instance, as the screw and nut N. The stationary pinions E E are of one-half the diameter of the rotating gears F F.

In the modification illustrated in Fig. 3

the crank-shaft is made in two separate poitions D D, and each portion has its crank P P. The eccentric illustrated in Fig. 1 is replaced by two plates G, which have an cecentric groove V cut in each. These plates G are rigidly connected to the rotating gears 'F F and with them are mounted on studs S S on the cranks. The stationary pinions E E are mounted on the crank-shaft and by means of the flanges e e are fastened to the engine-frame and prevented from turning. The crank-pin p of Fig. l is replaced by the pin 2) in Fig. 3, which passes through the slots 3 s in the cranks and works in the eccentric cam-grooves V, before described. The connecting-rod H is connected directly to the pin 1) by the perforated end As before, the stationary pinion is on e-half the diameter of the rotating gear which meshes with it.

A second modification (illustrated in Fig. 6) is designed to afford connections for operating the exhaust-valve. The portion D of the crank-shaft is solid and only the portion D rendered hollow. Through this hollow portion the stud (1 extends to support the stationary pinion E, as before, and is held in place by the nut N. On the hollow portion 1) of the crank-shaft is the external gear J, which meshes with the gear K on the shaft 70, which transmits motion to the exhaust-valve in any one of the well-known ways.

Figs. 7 to 10 represents a third modification, in which a portion of the teeth on the stationary gear is removed. One half of the circumference M has teeth, while the other half m is left blank. The rotating gear F is in this case only one-half the diameter of the stationary gear E. The operation of the various forms of my invention is as follows: In the apparatus shown in Figs. 1 to 6 the eccentric G is supposed to be turned upward at the beginning of the power stroke of the engine-that is to say, the stroke during which explosion takes place. During the succeeding revolution of the crank-shaft the rotating gear F has made one-half of a revolution on its axis in rolling around the stationary gear E. Consequently at the end of the succeeding return stroke the eccentric G has been turned downward and the piston is driven to the bottom of the cylinder and all the burned gases expelled. During the succeeding revolutions, which is composed of the outstroke, which sucks in the charge of gas, and the instroke, which compresses it, the rotating gear F has been turned another one-half revolution and the eccentric Gis again turned upward, so that the piston is not forced to the end of the cylinder, but stops short, leaving a space in which the charge of gas is compressed ready for explosion.

In the apparatus illustrated in Figs. '7 to 10 the engine is supposed in Fig. 7 to be at the point of explosion. The rotating gear F being left free during the outstroke, (as there are no teeth on the portion on in the stationary gear,) the compression of the connectingrod caused by the explosion in the cylinder keeps the eccentric G in the same position, and it arrives at the end of the first revolution in the position shown in Fig. 8. During the return stroke by which the gases are to be expelled, the rotating gear F is engaged by the teeth on the portion M of the stationary gear, and as the diameters are in the proportion of one to two the said rotating gear is given one complete revolution. It therefore arrives at the end of the second one-half revolution in the position shown in Fig. 9, thereby forcing the piston to the end of the cylinder. During the third onehalf revolution the rotating gear F is again free, and as the suction of drawing in the charge produces a strain of tension in the connecting-rod II, the eccentric G remains in the same position and arrives at the end of the third one-half revolution in the position represented in Fig. 1 During the fourth one half revolution, in which the charge is compressed, the rotating gear and eccentric make another complete revolution and arrive at the bottom of the stroke in the position represented in F1g. 7, ready for the explosion of the charge and a repetition of the above-described cycle of operations.

The advantages of my invention are numerous, and there are various applications in which it could be used. The special advantage in its application to gas-engines is that it gives a variable piston motion, such that a complete clearing out of the cylinder at every other stroke is possible, so that a poorer quality of gas may be used, and the inequality of action of the engine due to the heating of the incoming charge before compression by the portion of burned gases in the cylinder is avoided.

It is evident, of course, that in the form of invention illustrated in Figs. 7 to 10 the gearteeth could be dispensed with and simple friction-gearing could be used in the place of teeth.

Having therefore described my invent-ion, what I claim as new, and desire to protect by Letters Patent, is-

1. In a variable crank-motion, the combination of the crank-arm, the rotating gear mounted thereon, the stationary pinion of one-half the diameter of the gear, the eccentric rigidly connected to said rotating gear, and the connecting-rod operated by said eccentric, substantially as described.

2. In a variable'crank-motion, the combination of the engine-bed with double-crankshaft bearings, the cylinder and piston, the crank and crank-shaft, one portion of which latter is hollow, the rotating gear mounted on the crank-pin, the eccentric cast integral therewith, the connecting-rod connected to said eccentric, the stationary pinion of 011ehalf the diameter of the rotating gear, and the spindle on which the pinion is mounted, which pinion extends through the hollow portion of the crank-shaft and is rigidly connected with the engine-bed, substantially as described.

3. In a variable crank-motion for gas-engines, the combination of the engine bed with double-crank-shaft bearings, the cylinder and piston, the crank and crank-shaft, one portion of which latter is hollow, the rotating gear mounted on the crank-pin, the eccentric cast integral therewith, the connecting-rod connected to said eccentric, the stationary pinion of one-half the diameter of the rotating gear, and the spindle on which the pinion is mounted, which pinion extends through the hollow portion of the crank-shaft and is rigidly connected with the engine-bed, crank-pin for each revolution of the crank, 10 together with an external gear on the hollow substantially as described.

portion of said crank-shaft and the meohan- In testimony whereof Iaffix my signaturein ism which conveys motion to the exhaustpresence of two Witnesses. valves, substantlally as descrlbed. ARTHUR KITSON 4. In a variable crank-motion, the combi nation of a crank-pin, an eccentric fitted on Witnesses:

said crankpin,and mechanism which causes E. CLINTON RHOADS, said eccentric to make a half-turn on the EVAN J LESTER. 

